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[SCCP] Fold constants as we build them whne visiting cast instructions.

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This should be slightly more efficient and could avoid spurious overdefined
markings, as Eli pointed out.

Differential Revision:  http://reviews.llvm.org/D22122

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@274905 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Davide Italiano 2016-07-08 19:13:40 +00:00
parent 9ea0ae7891
commit a5b3bc1479
2 changed files with 13 additions and 2 deletions
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6
lib/Transforms/Scalar/SCCP.cpp
View File

@ -760,8 +760,10 @@ void SCCPSolver::visitCastInst(CastInst &I) {
if (OpSt.isOverdefined()) // Inherit overdefinedness of operand
markOverdefined(&I);
else if (OpSt.isConstant()) {
Constant *C =
ConstantExpr::getCast(I.getOpcode(), OpSt.getConstant(), I.getType());
// Fold the constant as we build.
Constant *C = ConstantFoldCastOperand(
I.getOpcode(), getValueState(I.getOperand(0)).getConstant(),
I.getType(), DL);
if (isa<UndefValue>(C))
return;
// Propagate constant value

9
test/Transforms/SCCP/bitcast.ll Normal file
View File

@ -0,0 +1,9 @@
; RUN: opt < %s -ipsccp -S | FileCheck %s
define i128 @vector_to_int_cast() {
%A = bitcast <4 x i32> <i32 1073741824, i32 1073741824, i32 1073741824, i32 1073741824> to i128
ret i128 %A
}
; CHECK: define i128 @vector_to_int_cast(
; CHECK-NEXT: ret i128 85070591750041656499021422275829170176